1. Field of the Invention
This invention relates to a gas pressure regulator provided with a mechanism for easily changing a set pressure value when the type of gas being supplied is changed.
2. Description of the Prior Art
A gas pressure regulator is used, for example, in the supply line of a gas burner for reducing the incoming pressure of a gaseous fuel to a predetermined regulated value. However, when the type of gas being used is converted from city gas to liquefied petroleum gas (LPG) or conversely, the regulated or secondary pressure setting must be changed to maintain desired combustion conditions.
In the past, the resetting of such secondary pressure has been carried out by measuring the secondary pressure while suitably adjusting a threaded regulating rod when the gas type conversion is made. Such a construction has been employed in gas pressure regulators disclosed in Japanese Utility Model Application Publication Nos. 92740/78 and 14839/76.
FIG. 1 schematically shows a conventional gas pressure regulator as described in the No. 92740/78 Publication, wherein reference numeral 1 designates a housing which comprises a lower cup 1A on the gas side provided with an inlet 5 and an outlet 6, and an upper cup 1B on the pressure regulating side provided with a pressure regulating rod 7 which will be described later. A diaphragm 2 is clamped between the upper and lower cups, and two spring seats 3A and 3B are provided in the central portion of the diaphragm. A valve 4 having a stem 4a is connected to the spring seat 3A.
The pressure regulating rod 7 is mounted in a threaded hole 10 in the upper cup 1B, and carries a spring seat 9 at one end for engaging a pressure regulating spring 8 disposed between it and the seat 3B. Reference numeral 11 designates a supply source for city gas or LPG, 12 is a gas supply valve, 13 is an electromagnetic valve, 14 is a gas burner, 15 is a gas line, P.sub.1 is the primary gas pressure, and P.sub.2 is the secondary gas pressure.
In such a conventional gas pressure regulator the adjustment or resetting of the secondary pressure P.sub.2 is accomplished by screwing the pressure regulating rod 7 in or out while measuring the secondary pressure with a gauge. Such mode of adjustment is obviously troublesome and time consuming.